Sequelize GraphQL

This is a simple set of helper functions that will recursively traverse a GraphQL query and create the optimal Sequelize findAll options for include, where, attributes, limit, and orderBy. A complex GraphQL query can often be resolved with a single SQL query, maximizing performance.

See Also

• Sequelize Query Docs: https://sequelize.org/v5/manual/querying.html
• Alternative approach without Sequelize: https://github.com/acarl005/join-monster
• Facebook's DataLoader: https://github.com/graphql/dataloader

Example

SQL Schema

CREATE TABLE `person`
(
  `id`              int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name`            varchar(255)   NOT NULL DEFAULT '',
  `best_friend_id`  varchar(255)   NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  CONSTRAINT `best_friend_fk`
    FOREIGN KEY (`best_friend_id`)
    REFERENCES `person` (`id`) ON DELETE SET NULL ON UPDATE CASCADE
) ENGINE = InnoDB;

GraphQL Schema

enum OrderDirection {
  ASC
  DESC
}

input ColumnOrder {
  col: String,
  dir: OrderDirection
}

type Person {
  id: Int
  name: String
  bestFriendId: Int
  bestFriend: Person
}

type Query {
  people(where: JSON, orderBy: [ColumnOrder], limit: Int, offset: Int): [Person]
}

Sequelize Model

import {
  Model,
  Association,
  DataTypes,
  Sequelize
} from "sequelize";

export class Person extends Model {
  public id!: number;
  public name!: string;
  public bestFriendId!: number;
  public readonly bestFriend!: Person;

  public static associations: {
    bestFriend: Association<Person, Person>;
  };
}

export default (sequelize: Sequelize) => {
  Person.init({
    id: {
      type: DataTypes.INTEGER.UNSIGNED,
      primaryKey: true,
      autoIncrement: true,
      allowNull: false
    },
    name: DataTypes.STRING(255),
    bestFriendId: DataTypes.INTEGER.UNSIGNED
  }, {
    underscored: true,
    tableName: 'person',
    sequelize: sequelize
  });

  return Person;
};

Resolver

const resolvers: IResolvers = {
  Query: {
    people: (source, args, context: GraphQLContext, info): Person[] => {
      return context.db.Person.findAll(getSequelizeQuery(args, info, context.db.Person));
    }
  }
};

Query

query {
  people {
    id
    name
    bestFriend {
      id
      name
      bestFriend {
        id
        name
      }
    }
  }
}